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Power Umbilical Qualification

Power umbilicals have an extremely important role in offshore applications, being responsible for the energy transfer between the production platforms and subsea equipment, for example. These cables are flexible structures composed by different layers, being able of withstanding high strains without failing.

Depending on the situation, the umbilical cables can be designed for static or dynamic applications. In applications where these devices are under dynamic loads, the damage related to the fatigue phenomenon can occur. Therefore, it is extremely important to verify and validate the methodologies adopted during the design phase of these components.

In 2014, Símeros in a partnership with the Physical Metallurgy Laboratory (LAMEF) of the Federal University of Rio Grande do Sul (UFRGS) was responsible for the project and execution of tests related to the qualification program of a power umbilical to be installed in the west coast of the Unites States. The qualification program’s focus was, primarily, to confirm the mechanical properties of the umbilical cable, verify if the electrical properties were kept after the dynamic loads, validate the local numerical model used in the design phase and verify if the umbilical concept adopted was adequate for the installation.

 

 

During the qualification program, several small-scale and full-scale tests were performed, following the guidelines available in API 17E and in the client’s specifications. Among the tests carried out, the following can be highlighted:

  • Small-scale static tests to determine the tensile armour and copper conductors’ mechanical properties.
  • Small-scale fatigue tests of the tensile armour and copper conductors to confirm the S-N curves adopted in the design phase.
  • Small-scale test to evaluate the external plastic sheath’s wear when in contact with metallic surfaces.
  • Full-scale static crush test and friction coefficient evaluation between the umbilical cable and the pads used in the tensioner during installation.
  • Full-scale static tests to determine global mechanical properties of the power cable, i.e., axial, torsional and bending stiffness.
  • Full-scale dynamic tests to confirm the structural integrity of the equipment during its expected service life.

Related articles:

  1. Submarine Power Cable Design Validation through Model Testing (https://www.onepetro.org/conference-paper/ISOPE-I-16-576)
  2. Submarine Power Cable Bending Stiffness Testing Methodology (https://www.onepetro.org/conference-paper/ISOPE-I-16-579)
  3. Validation of Power Cable Local Stress Analysis (https://www.onepetro.org/conference-paper/ISOPE-I-16-592)